CLADDING // CONCRETE // INSULATION // STEEL // THATCH // TIMBER // TRANSLUCENT // WATERPROOFING // COMPONENTS
FEATURES
“ Compartmentation is a very important requirement very often neglected at the top floors of multi-tenancy buildings including hotels, hostels, offices, flats and more. Public buildings require special consideration, and in some applications not permitted in terms of the National Building Regulations,” says Strydom.
Timber a safer choice
The aftermath of the Cape fires led to a lull in the local timber economy – more than a million cubic metres of timber was lost from South Africa’ s annual supply. On the positive side, the use of timber in construction is on the rise.
The ITC-SA states while there are a few misconceptions around timber’ s fire performance, structural timber for roofing is both commonplace and performs well under fire conditions. As with every aspect of building, timber roof trusses must be manufactured and erected in line with the National Building Regulations and SANS 10400, which provide for fire safety.
“ Building regulations, set in place by bodies such as the South African Bureau of Standards( SABS) after extensive research and consultation with industry experts, consider all aspects of a given building material’ s composition and properties to ensure that it meets the same safety and performance standard as any other building material in the same application,” highlights the ITC-SA.
“ There is a significant market in South Africa for timber-framed housing and log homes with thatch roofs. Steps can be taken to minimise the fire risk to these properties by using new innovations in fire retardants,” notes Strydom.
He adds that timber or log-home buildings with external walls treated with fire retarded treated timber as well as treated thatch boast a reduced fire load of up to 50 %, therefore allowing safety distances to be reduced by up to a third.
“ It is legal to use timber trusses for many applications in terms of the National Building Regulations. The use of timber trusses has challenges to consider if used in multi-occupancy and multitenancy structures. Fire divisions have to be addressed properly as to prevent the spread of fire.
“ Although timber is combustible it can be used safely for stability which is the major consideration. Timber trusses can withstand fire better than light-weight steel roof structures. This is also applicable to light-weight steel buildings which are commonly found today,” explains Strydom.
Fire prevention and treatment
Strydom highlights that timber trusses are only one of the components for a roof structure as the roof covering could either be combustible or noncombustible. Should both be present like a thatch roof construction, both the truss and the thatch covering should be treated.
“ Thatched roofs are not the only combustible roof known, hence the test method, SANS 10177-12, for combustible roofs as stipulated in the National Building Regulations, SANS 10400-T. To prevent combustible roofs, trusses and the thatch layer from being ignited, it can be treated with a suitable approved fire retardant( FR) or protective FR treatment,” says Strydom.
Strydom says the treatment of the timber used for the construction of the roof structure must be treated using an industrial treatment process called vacuum-pressure impregnation( VPI). The process is similar to that of preservation treatment, SANS 457. Strydom adds that thatching grass used for the construction of thatch roofs can also be treated using the same VPI process as a permanent fire retardant option for the life of the thatch layer.
Tech putting out fires
Technology is available and can be used very effectively for most applications, says Strydom. However, it is not commonly known or ignored in most instances, he adds. Despite this, South Africa is a world leader with regards to fire retardant treatment of timber or cellulosic materials, he notes.
Strydom continues,“ There are fire prevention requirements available in legislation and many technologies that can be utilised in the prevention and fighting of fires. The technologies available vary from techniques used in the fighting as well as additives to water in minimising losses.”
Pexels
Countries affected by global warming, such as Africa and Australia, will increasingly experience detrimental bushfires.
COMMON CAUSES OF FIRES WITHIN THE BUILT ENVIRONMENT
• Human negligence
• Poor maintenance
• Bad housekeeping
• Electrical – negligence, bad maintenance or illegal installations
• Arson – very common and fraudulent insurance related
• Natural disasters – lightning, veld and bush fires
• Unattended fires
FIRE REGULATIONS RELATING TO TIMBER ROOF TRUSSES
• Each independent dwelling unit situated on either side of a fire wall must have its own bracing system within its roof structure, regardless of the fire wall projecting above the roof covering or not.
• The fire regulations do not state the size of a permissible gap between timber members bearing on either side of the fire wall. However, trusses passing through a fire wall must be split into separate trusses.
• The regulation states that no part of the roof assembly, made of wood or any other combustible material shall pass through the separating wall.
• No tile underlay or insulation may pass over the fire wall.
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AUGUST 2018